I personally still have no idea how alchemy works either, as I keep waiting to see if I'll get better alchemy rituals.
You need to progress in the story to get more, and meet the same condition you meet the time you unlocked the feature at all (die). I got enough rituals already, but guessing formulas and guessing archetype conditions gets tiring really, really fast, specially given how cryptic some are. Creating new lvl 50 dolls and experimenting with different stats over and over and praying to hit the nail is a bit excessive.
I just hope some tool or book or unlockable later gives more meaningful hints to figuring out some of those.